The Thermal Conductivity Tensor of β‐Ga2O3 from 300 to 1275 K

Laser‐flash measurements of the thermal conductivity λ(hkl)$\lambda _{(hkl)}$ of Czochralski‐grown β‐Ga2O3 single crystals are reported perpendicular to four independent crystallographic lattice planes (hkl)=(2¯01)$(hkl)=(\bar{2}01)$ , (010), (001), and (100) between room temperature and 1200 K. λ is represented by a symmetric tensor of rank 2 and has four independent components. Tensor components λ11=λ(100)=12.13$\lambda _{11}=\lambda _{(100)}=12.13$ W m−1 K−1 and λ22=λ(010)=24.26$\lambda _{22}=\lambda _{(010)}=24.26$ W m−1 K−1 (values for 300 K) can be directly measured. λ33=14.09$\lambda _{33}=14.09$ W m−1 K−1 and λ13=−0.992$\lambda _{13}=-0.992$ W m−1 K−1, instead, are obtained by combining λ(001)=13.53$\lambda _{(001)}=13.53$ W m−1 K and λ(2¯01)=14.33$\lambda _{(\bar{2}01)}=14.33$ W m−1 K. The crystallographic b⃗$\vec{b}$ ‐axis is the direction with the highest thermal conductivity, λ22. The thermal conductivity assumes its lowest value (11.73 W m−1 K−1) in a direction close to the crystallographic a⃗$\vec{a}$ ‐axis. However, this direction does not coincide with a⃗$\vec{a}$ , and changes with temperature.

[1]  D. Klimm.  Thermal Analysis and Thermodynamics , 2022 .

[2]  Z. Galazka.  Growth of bulk β-Ga2O3 single crystals by the Czochralski method , 2022, Journal of Applied Physics.

[3]  M. Scarpulla,et al.  The anisotropic quasi-static permittivity of single-crystal β-Ga2O3 measured by terahertz spectroscopy , 2020, Applied Physics Letters.

[4]  Ronggui Yang,et al.  Three-dimensional anisotropic thermal conductivity tensor of single crystalline β-Ga2O3 , 2018, Applied Physics Letters.

[5]  M. Hanke,et al.  Thermal expansion of single-crystalline β-Ga2O3 from RT to 1200 K studied by synchrotron-based high resolution x-ray diffraction , 2018, Applied Physics Letters.

[6]  Ronggui Yang,et al.  Three-Dimensional Anisotropic Thermal Conductivity Tensor of Single Crystalline \b{eta}-Ga2O3 , 2018, 1809.04762.

[7]  J. Muth,et al.  Anisotropic thermal conductivity of β-Ga2O3 at elevated temperatures: Effect of Sn and Fe dopants , 2017 .

[8]  J. Albrecht,et al.  Erratum: “Lattice thermal conductivity in β-Ga2O3 from first principles” [Appl. Phys. Lett. 107, 041907 (2015)] , 2016 .

[9]  John D. Albrecht,et al.  Lattice thermal conductivity in β-Ga2O3 from first principles , 2015 .

[10]  F. Bechstedt,et al.  Dielectric tensor of monoclinic Ga2O3 single crystals in the spectral range 0.5–8.5 eV , 2015, 1507.05401.

[11]  R. Mitdank,et al.  Temperature-dependent thermal conductivity and diffusivity of a Mg-doped insulating β-Ga2O3 single crystal along [100], [010] and [001] , 2015, 1506.05294.

[12]  D. Jena,et al.  Anisotropic thermal conductivity in single crystal β-gallium oxide , 2014, 1412.7472.

[13]  Reinhard Uecker,et al.  On the bulk β-Ga2O3 single crystals grown by the Czochralski method , 2014 .

[14]  R. Mitdank,et al.  Temperature-dependent thermal conductivity in Mg-doped and undoped β-Ga2O3 bulk-crystals , 2014, 1407.4272.

[15]  P. Paufler.  Physikalische Kristallographie , 1986 .

[16]  G. M. Wolten,et al.  Determination of the point group of β-Ga2O3 from morphology and physical properties , 1976 .

[17]  R. J. Jenkins,et al.  Flash Method of Determining Thermal Diffusivity, Heat Capacity, and Thermal Conductivity , 1961 .

[18]  S. Geller,et al.  Crystal Structure of β‐Ga2O3 , 1960 .

[19]  Rustum Roy,et al.  Polymorphism of Ga2O3 and the System Ga2O3—H2O , 1952 .

[20]  L. Pauling,et al.  THE CRYSTAL STRUCTURES OF HEMATITE AND CORUNDUM , 1925 .

[21]  H. Dachs.  Die Kristallstruktur des Bixbyits (Fe,Mn)2O31 , 1956 .

[22]  W. Zachariasen.  XXXI. Über die Kristallstruktur von Bixbyit, sowie vom künstlichen Mn2O3 , 1928 .